Shell Programming and Scripting

Why the following code printing duplicate records?

bash-4.1$ cat rm1

Code:

        c1      c2      c3
l1      2       3       4
l2      2       3       2

bash-4.1$ awk '{print $0} OFS = "\n"' rm1

Code:

        c1      c2      c3
        c1      c2      c3
l1      2       3       4
l1      2       3       4
l2      2       3       2
l2      2       3       2

The awk script:

Code:

awk '{print $0} OFS = "\n"' file

can be more clearly written in this case as:

Code:

awk '
	{print $0}
OFS = "\n"
' file

Since there is no condition on the line {print $0} the action is performed for every input line. And, since the condition on the next line (OFS = "\n") evaluates to a non-zero value for every line read, the default action ({print $0}) is also performed for every input line. Therefore, your script prints every line twice.

If you're trying to print each input field as a separate output line, you need to do something to cause the input line to be re-evaluated; perhaps you intended something like:

Code:

awk '{$1 = $1}1' OFS="\n" file

Note that the OFS="\n" is outside the single quotes and the spaces around the equal sign have to be removed when using this form.

@Akshay: Oh i have no problem with the code. However, I would like to understand the logic behind duplicate records.
@Don: Hi DOn, Thanks. Could you please explain the logic behind. Also how did you manage to put "small code tags" ?

Code:

'{$1 = $1}1'

Thanks but what about this ?

Code:

'{$1 = $1}1'

I'm not sure what you mean by "small code tags", but the button marked </> at the far right at the top of your editing screen when editing or creating a new post produces [ICODE] and [/ICODE] tags which use the same font and background color used by the [CODE] and [/CODE] tags, but do not force a line break.